Some places will introduce you to everyone that is available (and not preoccupied with someone in another room).  For me, it's also for future research and to see how much photoshopping has been done.   Recently, it isn't the old meet and greet in a large sitting area but you go directly to the room and the girls just pop in to say hello one by one (don't forget their names!) and then you choose.  

Now that I think about it, that 10 second screening serves another purpose.  I wasn't sure who I wanted to see, so I asked for the brief intros.  The girl with the "best" pictures who I thought I wanted to see gave me a cursory hello and body language that said "You interrupted my TV show and I'd rather be doing that."  The girl who was a little older with less attractive pictures gave me smile, a hug, a warm 'Nice to meet you!' and positive vibes that played out in the room as I chose her.  

You're right.  In a way, the girls get to choose by directing a customer's reaction just as I described. If she doesn't think she'll like being with you or she isn't feeling well that day she can send you the "pick someone else" message